Polybutene composition containing halo-carbonyl additives and use thereof

ABSTRACT

Viscous polybutenes of number average molecular weight (M n ) in the range of about 300 to about 3000 have improved reactivity with intramolecular anhydrides of unsaturated aliphatic dicarboxylic acids when reacted in the presence of rather small amounts, i.e., 5 to 200 ppm, of alpha halogen-containing, preferably chlorine or bromine-containing, aliphatic or aromatic carbonyls including acetals as additives. Use of such halogen-containing additives in the addition reaction of polybutene with said unsaturated anhydrides can reduce formation of undesired tarry product resulting from polymerization and/or thermal decomposition of the unsaturated anhydrides.

This is a division, of application Ser. No. 358,958, filed May 10, 1973,now U.S. Pat. No. 3,953,475.

BACKGROUND OF INVENTION

Viscous polybutenes of about 300 to about 3000 M_(n) have viscosities inthe range of about 4 to about 5500 centistokes at 100° C. Suchpolybutenes are commercially available from polymerization of refinerybutenes; isobutylene, cis-butene-2 and butene-1 generally present withbutane in a C₄ fraction. Commercially since about 1940, such C₄ fractionwith or without added isobutylene, or isobutylene rich concentrates hasbeen polymerized in the presence of Friedel-Crafts catalyst. The widerange in viscosity and molecular weight depends, as is known, onpolymerization temperature, to a lesser extent on catalyst and itsconcentration, and on the olefin content of the feed. The viscouspolybutenes are essentially water white and thermally decompose with noresidue at temperatures above 275° C. and have some use applications inengine oils and anti-scuff agents and viscosity index improvers and infuels for internal combustion engines to reduce or suppress deposits inthe fuel induction system.

The viscous polybutenes have also found use as components of caulkingcompounds, adhesives and electric-cable insulating oils. However, thegreatest use of the viscous polybutenes is as a raw material in themanufacture of addition agents for fuels and gasoline because theviscous polybutenes are reactive olefins and provide branched-chainalkyl structure in derivatives enhancing their solubility in petroleumproducts such as lubricant oils, fuels and refinery streams. Thederivatives of most interest in the past 15 years are from thepolybutenyl-substituted intra-molecular anhydrides of aliphaticdicarboxylic acids such as succinic anhydride. Thepolybutenyl-substituted saturated aliphatic anhydrides have been usedper se, or as diesters, amides, imides, amidines, imidines, and neutralor overbased basic metal salts as addition agents in petroleum products.The addition agents from polybutenes of M_(n) below 500 are mainly usedin fuels; for example in gasoline to inhibit rusting, carburetordeposits, and carburetor icing and in diesel fuels to inhibit rust,corrosion and smoke, and in motor oils and industrial oils as rust andwear inhibitors.

The addition agents from polybutenes of 500 to about 3000 M_(n) havefound extensive use as detergent-dispersants in motor oils and lesseruse as carburetor detergents in gasoline, heat exchanger antifoulants inrefinery streams, rust and corrosion inhibitors in surface coatings andas emulsifiers and demulsifiers.

The viscous polybutenes are complex mixtures of polymers, copolymers andinterpolymers of isobutylene, cis-butene-2 and butene-1. The nature andrelative amounts of the butene monomers involved in the polymerizationleading to a particular M_(n) polybutene are not indicative of theresulting polymer product because extensive isomerization occurs duringpolymerization. The viscous polybutenes, although largely mono-olefins,may contain 0 to 20% isoparaffins. The unsaturation in the viscouspolybutene molecules is predominantly in a terminal or near terminalgroup which, as later illustrated, are of the trisubstituted orvinylidene type. The non-olefinic chain portion of the polybutenemolecules is composed of normal butyl and isobutyl units and hence is along and branched alkyl chain. Such long, branched alkyl chain of thelighter (below 500 M_(n)) polybutenes contain relatively greater amountsof normal butyl units and lesser amounts of iso-butyl units. The heavier(500-3000 M_(n)) polybutenes contain relatively greater amounts ofisobutyl units and lesser amounts of normal butyl units which areconcentrated near the end of the long, branched alkyl chain. Forexample, the structures of a polydisperse polybutene of about 900 M_(n)have in part been identified through the use of infrared spectroscopy(calibrated by NMR) and permanganate cleavage. The principal structuresidentified are shown below (in decreasing order of concentration):##STR1## wherein R is the long, branched alkyl chain and comprises about60 mole % (C₄)₄ to 11, about 30 mole % (C₄)₁₂ to 35 and about 10 mole %(C₄).sub._(>) 35 ; R' is mainly methyl but is also ethyl; and the ratioof iso-C₄ to n-C₄ is about 3:1.

With respect to polybutene addition reactivity with unsaturatedintramolecular anhydrides, it is believed, that the olefinic terminalgroups in the three structures shown above are in the decreasingreactivity order of III, I and II. In the uncatalyzed addition reactionsome of the slower reacting molecular species remain unreacted and withthe isoparaffinic polymer species (0-20% of the total polymer product)which do not react at all, the desired polybutenyl-substituted saturatedanhydride product can be obtained in yields of 75-80% based on startingpolymer.

Such addition reaction between the viscous polybutene and intramolecularanhydride of unsaturated aliphatic dicarboxylic acid can typically useany one of maleic anhydride, citraconic anhydride, itaconic anhydride,ethyl maleic anhydride, halo (e.g., chloro-) maleic anhydride,glutaconic anhydride, homomesaconic anhydride, and the like according toU.S. Pat. Nos. 2,628,942 and 2,634,256 among others. The additionreactions are, in general, conducted at temperatures in the range of150° to 300° C. using polybutene to anhydride molar ratios of reactantsin the range of 1.0:1.0-15, generally 1.0:1.05-1.15. In addition to thenonreaction of some olefinic species of polybutene and isoparaffinicentities thereof amounting to a total of up to 40-50% of the polybutenecharged, there is also a problem with respect to thermal decompositionand polymerization of the unsaturated anhydride reactant at temperaturesupward from 150° C.

Thermal decomposition at temperatures upward from 150° C. of unsaturatedaliphatic dicarboxylic acids and their anhydrides (e.g. maleic and itsanhydride) has been known and is reported, for example in U.S. Pat. No.3,476,774 which gives earlier documentation sources therefor. Suchthermal decomposition is accompanied by evolution of water vapor andoxides of carbon, in a closed reaction vessel, is accompanied by anincrease in internal pressure. Under some observed conditions thethermal decomposition can be so substantially instantaneous as to beexplosive. In the absence of explosive thermal decomposition acarbon-containing residue is also formed in addition to water vapor andoxides of carbon. Such thermal decomposition and attendantpolymerization of the unsaturated anhydride reactant has been observedas occurring during its addition reaction with polymeric olefins, e.g.polybutenes and others, in a closed reaction vessel. There is theincrease of internal pressure by involved water vapor and oxides ofcarbon (mainly CO₂) but the attendant carbon-containing residue variesin nature from somewhat granular when the decomposition is only slightto a tarry material mainly adhering to internal surfaces of the reactionvessel when the decomposition is more extensive but well below explosivemagnitude. The granular type residue amounts to from about 0.1 to about0.3 weight percent of the total charge, in general, is dispersed in theproduct, the alkenyl-substituted saturated anhydride addition compounddiluted with unreacted components of the olefin polymer, is readilyseparated therefrom by filtration. However, the tarry residual product,which for the most part fouls the internals of the reaction vessel canbe as high as 2-3 weight percent of the total charge. The tarry residualmaterial not adhering to reactor internals fouls the filter andinterferes with filtration of the desired reaction product. Both typesof residue are undesirable because of the above noted foulingcharacteristics and because their formation results in yield reductionof the desired alkenyl-substituted anhydride addition product.

Various means have been proposed and/or used to suppress thermalconversion of unsaturated anhydride reactant. German Pat. No. 1,102,142for its reaction of triene (e.g., 1,5,9-cyclododecatriene) with maleicanhydride to prepare a 1:1 addition product teaches the use of from 0.01to 5 weight percent of thionine, phenothiazine, hydroquinone, andrelated inhibitors. U.S. Pat. No. 3,231,587 teaches the use of chlorinegas in molar amounts equal to maleic anhydride for its addition reactionwith olefin polymers (the resulting alkenylsuccinic anhydride contains0.4-0.5 weight percent chlorine) as a superior to earlier proposed firstpreparing a chlorinated olefinic polymer having 4-15 weight percentchlorine and reacting the chloro-polymer with maleic anhydride. U.S.Pat. No. 3,476,774 teaches the use of a hindered phenol nonreactive withthe olefin polymer or maleic anhydride (e.g. 2,6-ditertbutylphenol or4,4'-methylenebis-2,6-ditert-butylphenol) to suppress thermaldecomposition.

Such hindered phenols are not readily removed from the adduct product.The chloro-substituted adduct may not be useful in all cases for thepreparation of addition agent derivatives.

In our laboratories the use of small, i.e., catalytic amounts ofhydrogen chloride during the adduct formation between olefinic polymerand maleic anhydride achieved success in improving yield and reducingformation of undesired tarry material. A drawback of this method is thepossible corrosive nature of the stored product. However, it isunderstood, that hydrogen halides can react with the olefinic polymerforming alkyl halides. It is also recognized, that at highertemperatures, due to decomposition of the alkyl halides, hydrogen halideand halogen formation are possible. Hence it is recognized, thataddition of trace quantities of hydrogen halide or halogen or alkylhalides to the polymer could achieve the desired improvement in theaddition reaction. It was also recognized, that the effectiveness ofsuch halo-compounds will vary with process conditions and exact chemicalnature and concentration of the added material.

From the standpoint of both the manufacturer-merchant of the viscouspolybutenes and the purchasers-users thereof it would be desirable tomodify such polybutene compositions by addition of a small amount ofmaterial which enhances reactivity of the polybutene and suppressesformation of the undesirable tarry material without undesirable addedeffects. It would be further desirable that such modification of thepolybutenes be accomplished by a simple, single process step of not onlycombining a small amount of material with the polybutene to effect thedesired reactivity enhancement and tarry material suppression but alsoby use of a material which is readily removable from the adduct reactionproduct. For this latter benefit it is pointed out that unreactedanhydride, including that used in slight molar excess per mole ofpolybutene, is removed from the adduct reaction product by evaporationat an absolute pressure in the range of 5 to 760 mm Hg. and at atemperature below reaction temperature. Thus it is beneficial to add tothe polybutene such material having the above-beneficial effects on theadduct reaction and at the same time readily removable at saidtemperature and pressure conditions at which unreacted unsaturatedanhydride is removed.

SUMMARY OF INVENTION

It has now been discovered that viscous polybutenes of from about 300 to3000 M_(n) containing 10 to 200, preferably from 5 to 200 ppm on weightbasis of halogen, more suitably chlorine and/or bromine, containingaliphatic or aromatic ketones or acetals provides a novel, uniquelymodified polybutene composition. Such polybutene composition can bereacted at temperatures of 150°-300° C. with unsaturated anhydridewithout effecting chemical substitution of either the reactants or theadduct product, the halo-additive can be removed from the adduct productunder conditions of removing unreacted unsaturated-anhydride, enhancespolybutene conversion to adduct, and suppresses tarry materialformation.

To be most readily removable with unreacted unsaturated anhydride at 10to 760 mm Hg., the halo-hydrocarbon added to viscous polybutene shouldhave sufficient vapor pressure at such pressures to facilitate theirremoval. Preferred as chloro- or bromo- aliphatic or aromatic ketonesacetals are those having a normal (atmospheric pressure) boiling pointup to 225° C. but it can be as low as 40° C.

Typical, but not all inclusive, of such chlorinated and/or brominatedaliphatic or aromatic ketones and acetals are:

(A) The halo-ketones typically are alpha-chloro or -bromo ketones anddi(alpha-chloro- or bromo) ketones. The former include mono, di- andtri-alpha chloro- or bromo-acetone; mono- and di-alpha chloro- or bromo-methylethyl ketone, diethyl ketone, methylpropyl ketone, ethylpropylketone, ethylisopropyl ketone, diisopropyl ketone, di-n-propyl ketone,methyl n-butyl ketone, ethyl isobutyl ketone, methyl tert. butyl ketone,n-butyl isopropyl ketone, n-propyl isobutyl ketone, n-propyl tert. butylketone, di-n-butyl ketone, diisobutyl ketone, etc. of the symmetricaland mixed alkyl ketones having in addition to the keto carbonyl carbonup to a total of twenty carbon atoms. The alpha-chloro- or bromo-alkyldiketones are those having two keto-carbonyl carbons in a chain ofcarbon atoms which are otherwise alkyl as in a chain of 4 to 22 carbonatoms wherein the chlorine or bromine atom or atoms is attached to achain carbon adjacent to a keto carbonyl carbon. Such alpha chloro- orbromo-diketones are illustrated by 1,4-dichloro ordibromo-2,3-butanedione; 1,5-dichloro ordibromo-3,3-dimethyl-2,4-pentanedione; 2,6-dichloro ordibromo-4,4-dimethyl-3,5-hexanedione; 2,6-dichloro ordibromo-4,4-dimethyl-3,5-heptanedione; 1,4-dichloro- ordibromo-2,3-pentanedione; 2,5-dichloro- or dibromo-3,4-hexanedione, andthe like. The alpha-chloro- or bromo aromatic ketones are preferablymixed alkyl aryl ketones with the chlorine or bromine on the alpha alkylcarbon as in alpha-chloro or alpha-bromo acetophenone, alpha-chloro- oralpha-bromo acetonaphthone, and the like.

(B) The alpha-chloro or alpha-bromo acetals are preferably C₁ -C₁₀dialkyl acetals of alpha-chloro- or alpha-bromo- acetaldehyde becausethe acetaldehyde acetals are more available than acetals of otheraldehydes. Of such preferred alpha-chloro or alpha-bromo- acetaldehydediethyl acetals are most preferred.

The reaction between the viscous polybutenes and the anhydrides ofunsaturated aliphatic dicarboxylic acids known to the art to be usefulfor the addition reaction producing alkenyl-substituted saturatedanhydride, is conducted commercially in a batchwise or continuous mannerin a stirred-tank type autoclave or equivalent reaction vessel providingintimate contact between the reactants. For batchwise operation thereactants are charged to the closed reaction vessel with or withoutdisplacing its air with oxygen-free, e.g. nitrogen, atmosphere atambient pressure. The reactants can be at ambient temperature but thepolybutene reactant is usually at an elevated temperature to reduce thetime for the reaction mixture to reach reaction temperature. Solidanhydride reactant can be charged alone or dispersed in the polybuteneor alone as a melt. The reaction mixture is stirred while being heatedto reaction temperature and during reaction.

Continuous conduct of the addition reaction is maintained by charging tothe reaction vessel containing the stirred adduct forming reactionmixture a melt of the anhydride reactant and preheated viscouspolybutene so that their combined heat supplies the heat input neededduring reaction.

Reaction time for batchwise operation is, in general, 4-8 hours.Continuous operation requires, in general, a shorter residence time, forexample 1-3 hours.

Thermal decomposition of anhydride reactant, which evolves CO₂ and watervapor, causes an undesirable pressure increase as well as formation ofundesirable tarry material during the adduct reaction. Such pressureincrease, although undesirable, can be used as an indicator of failureto suppress formation of such tarry material by the additive of thepolybutene composition. The actual extent of formation of such tarrymaterial is, of course, determined gravimetrically after termination ofthe addition reaction and removal of unreacted anhydride reactant at thebefore mentioned pressure in the range of 5 to 760 mm Hg.

The manner and nature of enhanced adduct yield by the alpha-halo ketoneor acetal additive is not understood. We speculate that isomerization ofthe olefin double bond to a more reactive species is accomplished underthe effect of trace decomposition products derived from thealpha-chloro- or alpha-bromo ketone or acetal. Further, such traceimpurities can also act as radical quenchers and inhibit thedecomposition or polymerization of unsaturated anhydride to tar.

The present inventive use of the alpha-chloro or alpha-bromo- ketones oracetals and the benefits to be derived therefrom in addition reactionswith the before mentioned unsaturated anhydride will now be illustratedusing maleic anhydride, the most commonly, commercially used of thoseanhydride reactants. These examples were conducted in small reactivityscreening tests using a 22 ml volume Parr bomb having a magneticstirrer. In each illustrative example 10.0 grams of polybutene and about1.1 grams of powdered maleic anhydride (MA) to provide a polymer: MAmole ratio of 1.0:1.1 were charged. The air was displaced from the bombwith nitrogen, the bomb scaled and immersed in a 249° oil bath, thereaction mixture stirred for six hours, and then sampled.

A weight aliquot portion of each reaction product so produced waschromotographed on silica gel column. The unreacted polybutene waseluted from the column with hexane and determined gravimetrically toallow the calculation of the weight percent of polybutene that reactedwith MA. The total tarry product produced was also determinedgravimetrically and calculated as weight percent of the total charge(polymer+ MA).

                                      TABLE                                       __________________________________________________________________________    EFFECT OF ALPHA-Cl OR Br KETONE OR ACETAL ON ADDUCT AND                       __________________________________________________________________________    TAR                                                                           Example               Concentration, ppm                                                                       Adduct                                                                             Tar,                                    Number                                                                             Additive Name    Additive                                                                           Cl Br Yield, %                                                                           wt. %                                   __________________________________________________________________________    1    None              0   0  0  63.3 1.3                                     2    1,4-Dibromo-2,3-butanedione                                                                    73   0  48 75.5 0.2                                     3    alpha-Bromoacetonaphthone                                                                      63   0  20 73.0 0.4                                     4    Chloro-acetaldehyde diethyl acetal                                                             150  35 0  64.8 1.4                                     5    alpha-Bromoacetophenone                                                                        76   0  30 72.3 0.2                                     6    alpha-Chloracetophenone                                                                        151  35 0  62.6 1.3                                     __________________________________________________________________________

The alpha brominated additives were superior both with respect to adductyield improvement and tar suppression as compared to alpha-chlorinatedadditives when used in the same magnitude of halogen concentration.

While the foregoing examples illustrate benefits afforded by presentinventive polybutene compositions containing viscous polybutenes havingM_(n) of 900-950, the use of other viscous polybutenes in the M_(n)range of about 300 to 3000 will provide polybutene compositionsaffording yield improvement and suppression of tarry material in themanner and nature above illustrated for the maleic anhydride reactionsillustrated. Similar benefits can be expected by the use of the presentinventive polybutene compositions with other of the before namedunsaturated anhydrides of aliphatic dicarboxylic acids. Furthermore, theuse of the more active alpha-bromo ketone or acetal additives canfurther, according to this invention, be extended to reaction of theunsaturated anhydrides with other 300-3000 M_(n) olefinic reactants(e.g., polypropenes).

Finally, the alpha-bromo ketone or acetal additives are equally usefulwhether they are added to the 300-3000 M_(n) olefin reactant, theunsaturated anhydride or mixtures thereof.

What is claimed is:
 1. A composition comprising 300-3000M_(n) polybuteneand based on the weight thereof as additive from 5 to 200 ppm of analpha-bromo dialkyl ketone having in addition to the keto-carbonylcarbon atom up to a total of twenty carbon atoms, oralpha-dibromo-substituted alkyl diketone wherein its two keto-carbonylcarbon atoms are in a chain of from 4 to 22 carbon atoms and eachbromo-substituent is on a chain carbon atom adjacent to a keto-carbonylcarbon atom, or alpha-bromo aceto-phenone or naphthone, or C₁ -C₁₀dialkyl acetal of alpha-bromo acetaldehyde which additive has a normalboiling point in the range of from 40° C up to 225° C.
 2. Thecomposition of claim 1 wherein the additive is1,4-dibromo-2,3-butanedione.
 3. The composition of claim 1 wherein theadditive is alpha-bromo-acetonaphthone.
 4. The composition of claim 1wherein the additive is alpha-bromo-acetophenone.